Systems, apparatuses, and methods for monochromatic display waveguides

ABSTRACT

The disclosed apparatus may include a waveguide configuration that may include (1) a coupling area having at least one coupling element configured to receive a plurality of monochromatic images, where each of the monochromatic images is of a predetermined wavelength of light, (2) a propagation area in which light, received via the at least one coupling element, moves within a length of the waveguide configuration, and (3) a decoupling area that extends along the propagation area and includes decoupling elements that project a polychromatic image toward an eyebox, where the polychromatic image includes the monochromatic images of the predetermined wavelengths of light. Associated systems and devices are also provided herein.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. ProvisionalApplication No. 62/620,432, which is entitled “SYSTEMS, DEVICES, ANDMETHODS FOR TILED MULTI-MONOCHROMATIC DISPLAYS” and was filed on Jan.22, 2018; U.S. Provisional Application No. 62/620,434, which is entitled“SYSTEMS, APPARATUSES, AND METHODS FOR MONOCHROMATIC DISPLAY WAVEGUIDES”and was filed on Jan. 22, 2018; and U.S. Provisional Application No.62/620,435, which is entitled “SYSTEMS, APPARATUSES, AND METHODS FORCOMPONENT MOVEMENT IN MONOCHROMATIC DISPLAY DEVICES” and was filed onJan. 22, 2018. The entire contents of these provisional applications areincorporated herein by reference.

BACKGROUND

This disclosure relates generally to near-eye-display systems, and morespecifically to waveguide displays.

Near-eye light field displays typically project images directly into auser's eye, encompassing both near-eye displays (NEDs) and electronicviewfinders. Conventional near-eye displays (NEDs) generally have adisplay element that generates image light, using a multicolored pixelarray (including, e.g., red, green, and blue pixels), that passesthrough one or more lenses before reaching the user's eyes. The imagelight may be propagated laterally by a waveguide or other optical systemso that the display element does not need to be aligned directly with auser's eyes. Multicolored pixel arrays often use subpixels for eachcolor, which increases the distance between pixels but also creates aslight shift in pixel location for each color. With NEDs, thesedistances between pixels and shifts in location can be perceivable bythe user. Furthermore, it can be difficult to control light from apolychromatic display without creating chromatic aberrations.Additionally, NEDs in virtual reality systems and/or augmented realitysystems may have design criteria to be compact, light-weight, andhigh-resolution, and there may often be trade-offs made in attempt tosatisfy these criteria. Thus, conventional NEDs have not been entirelysatisfactory in all these regards.

SUMMARY

As will be described in greater detail below, the instant disclosuredescribes apparatuses, systems, devices, and methods that may utilizeone or more monochromatic emitter arrays to project monochromatic imagestoward a waveguide that may include one or more waveguide members. Insome embodiments, the monochromatic images may be combined in thewaveguide so that a desired polychromatic image is directed to theeyebox of a head-mounted display device.

In one example, an apparatus may include a waveguide configuration thatmay include (1) a coupling area having at least one coupling elementconfigured to receive a plurality of monochromatic images, where each ofthe monochromatic images is of a predetermined wavelength of light, (2)a propagation area in which light, received via the at least onecoupling element, may move within a length of the waveguideconfiguration, and (3) a decoupling area that may extend along thepropagation area and may include decoupling elements that project apolychromatic image toward an eyebox, where the polychromatic image mayinclude the monochromatic images of the predetermined wavelengths oflight.

In some embodiments, the waveguide configuration may include (1) a firstwaveguide that may include (a) a first top surface and (b) a firstbottom surface disposed opposite the first top surface. The waveguideconfiguration may further include (2) a second waveguide that includes(a) a second top surface and (b) a second bottom surface disposedopposite the second top surface. The propagation area may include (1) afirst propagation area portion between the first top surface and firstbottom surface and (2) a second propagation area portion between thesecond top surface and the second bottom surface.

In some examples, the at least one coupling element may include (1) afirst coupling element on the first waveguide and (2) a second couplingelement on the second waveguide. The first coupling element may beconfigured to receive a monochromatic image of a first predeterminedwavelength of light, and the second coupling element may be configuredto receive a monochromatic image of a second predetermined wavelength oflight. The first predetermined wavelength of light and the secondpredetermined wavelength of light may be different.

In some embodiments, the apparatus may further include (1) a firstmonochromatic emitter array having a plurality of emitters of the firstpredetermined wavelength of light disposed in a two-dimensionalconfiguration and (2) a second monochromatic emitter array having aplurality of emitters of the second predetermined wavelength of lightdisposed in a two-dimensional configuration. The first monochromaticemitter array may be aligned with the first coupling element, and thesecond monochromatic emitter array may be aligned with the secondcoupling element.

In some examples, the at least one coupling element may include (1) afirst coupling element and a second coupling element on the firstwaveguide, and (2) a third coupling element and a fourth couplingelement on the second waveguide, where the first coupling element isconfigured to receive a first monochromatic image of a firstpredetermined wavelength of light, the second coupling element isconfigured to receive a second monochromatic image of a secondpredetermined wavelength of light different from the first predeterminedwavelength of light, the third coupling element is configured to receivea third monochromatic image of the first predetermined wavelength oflight, and the fourth coupling element is configured to receive a fourthmonochromatic image of the second predetermined wavelength of light. Insome examples, the waveguide configuration may further include anoptical component disposed between the first waveguide and the secondwaveguide to introduce an apparent distance between a first image planeassociated with the first waveguide and a second image plane associatedwith the second waveguide.

The apparatus, in some embodiments, may further include an additionalcoupling area having an additional plurality of coupling elements, wherethe coupling area and the additional coupling area are disposed onopposite sides of the waveguide configuration.

In some embodiments, the at least one coupling element may include atleast one reflective optical element to direct at least one of themonochromatic images of the predetermined wavelengths of light into thepropagation area. In some examples, the at least one coupling elementmay include at least one refractive optical element to direct at leastone of the monochromatic images of the predetermined wavelengths oflight into the propagation area.

In some embodiments, the at least one coupling element may include atleast one set of gratings to direct at least one of the monochromaticimages of the predetermined wavelengths of light into the propagationarea.

In some examples, the propagation area may replicate the monochromaticimages to produce a plurality of pupil replications of the monochromaticimages, and the decoupling area may project the plurality of pupilreplications of the polychromatic image toward the eyebox.

In another example, a system may include (1) a first waveguideconfiguration including a first waveguide having a first top surface anda first bottom surface disposed opposite the first top surface, (2) afirst coupling element accessible via the first top surface of the firstwaveguide, the first coupling element configured to receive a firstmonochromatic image and propagate the first monochromatic imagelaterally within the first waveguide, (3) a first decoupling elementthat projects a plurality of instances of the first monochromatic imagetoward an eyebox, (4) a second waveguide having a second top surface anda second bottom surface disposed opposite the second top surface, wherethe first decoupling element projects the plurality of instances of thefirst monochromatic image through the second waveguide, (5) a secondcoupling element accessible via the second top surface of the secondwaveguide, the second coupling element configured to receive a secondmonochromatic image and propagate the second monochromatic imagelaterally within the second waveguide, and (6) a second decouplingelement that projects a plurality of instances of the secondmonochromatic image toward the eyebox, the pluralities of instances ofthe first and second monochromatic images being combined to produce aplurality of polychromatic images.

The system, in some implementations, may include a second waveguideconfiguration that may include (1) a third waveguide having a third topsurface and a third bottom surface disposed opposite the third topsurface, (2) a third coupling element accessible via the third topsurface of the third waveguide, the third coupling element configured toreceive a third monochromatic image and propagate the thirdmonochromatic image laterally within the third waveguide, (3) a thirddecoupling element that projects a plurality of instances of the thirdmonochromatic image toward an eyebox, (4) a fourth waveguide having afourth top surface and a fourth bottom surface disposed opposite thefourth top surface, where the third decoupling element projects theplurality of instances of the third monochromatic image through thefourth waveguide, (5) a fourth coupling element accessible via thefourth top surface of the fourth waveguide, where the fourth couplingelement is configured to receive a fourth monochromatic image andpropagate the fourth monochromatic image laterally within the fourthwaveguide, and (6) a fourth decoupling element that projects a pluralityof instances of the fourth monochromatic image toward the eyebox, thepluralities of instances of the third and fourth monochromatic imagesbeing combined to produce another plurality of polychromatic images,where the first and second waveguides are separated by a lens.

In some embodiments, the lens may be a variable focus lens having achangeable focal length that produces a changeable apparent distancebetween a first image plane associated with the first waveguideconfiguration and a second image plane associated with the secondwaveguide configuration.

In some examples, the second waveguide may include a cutout thataccommodates a housing of a first monochromatic emitter array thatproduces the first monochromatic image.

In some embodiments, the first waveguide configuration may have a curvedcross-sectional shape.

In one example, a device may include a head-mounted display including(1) a plurality of monochromatic emitter arrays, at least two of theplurality of monochromatic emitter arrays producing monochromatic imagesof different wavelengths of light, and (2) a waveguide configurationincluding (a) a top surface, (b) a bottom surface disposed opposite thetop surface, (c) a coupling area having at least one coupling elementconfigured to receive the monochromatic images, (d) a propagation areain which light received via the at least one coupling element moveswithin a length of the waveguide configuration and replicates themonochromatic images to produce monochromatic pupil replications, and(e) a decoupling area extending along the propagation area, thedecoupling area including decoupling elements that project a pluralityof instances of a polychromatic image toward an eyebox through thebottom surface, the polychromatic image resulting from combination ofthe monochromatic images of different wavelengths of light.

The device, in some embodiments, may further include a controller incommunication with the plurality of monochromatic emitter arrays toproduce the monochromatic images as components of the polychromaticimage.

In some examples, the top surface and bottom surface may permit ambientlight to pass toward the eyebox such that the plurality of polychromaticimages is presented to the eyebox and an ambient environment ispresented to the eyebox through the waveguide configuration.

The device, in some embodiments, may include a frame that secures thehead-mounted display to a user's head during use, with the waveguidebeing secured to the frame in an eyepiece.

Features from any of the above-mentioned embodiments may be used incombination with one another according to the general principlesdescribed herein. These and other embodiments, features, and advantageswill be more fully understood upon reading the following detaileddescription in conjunction with the accompanying drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings illustrate a number of exemplary embodimentsand are a part of the specification. Together with the followingdescription, these drawings demonstrate and explain various principlesof the instant disclosure.

FIG. 1 is a diagram of an HMD that includes a NED, according to someembodiments.

FIG. 2 is a cross-section of the HMD illustrated in FIG. 1, according tosome embodiments.

FIG. 3 is an isometric view of a NED having a waveguide configuration,according to some embodiments.

FIGS. 4A, 4B, and 4C are cross-sectional views of projector devices thatmay be included in the display system of FIG. 3, according to someembodiments.

FIGS. 5A, 5B, and 5C are top views of emitter arrays that may beincluded in the projector devices of FIGS. 4A-C, according to someembodiments.

FIGS. 6A and 6B are schematic cross-sectional diagrams of a microLEDincluded in the emitters arrays of FIGS. 4A-C and 5A-C, according tosome embodiments.

FIGS. 7A, 7B, 7C, and 7D are cross-sectional views of projector devicesand waveguide configurations, according to some embodiments.

FIG. 8 is a flowchart of a method of displaying an image in a displaysystem, according to some embodiments.

FIGS. 9A, 9B, and 9C are perspective views of NEDs, according to someembodiments.

FIG. 10A is a perspective view of another NED, according to someembodiments.

FIG. 10B is a cross-sectional view of the NED of FIG. 10A, according tosome embodiments.

FIGS. 11A, 11B, 11C, and 11D are cross-sectional views of a NED havingan actuation system, according to some embodiments.

FIGS. 12A, 12B, and 12C are portions of images generated by embodimentsof the NED of FIGS. 11A-D showing a process of resolution enhancement,according to some embodiments.

FIGS. 13A, 13B, and 13C are portions of images generated by embodimentsof the NED of FIGS. 11A-D showing another process of resolutionenhancement, according to some embodiments.

FIGS. 14A and 14B are portions of images generated by embodiments of theNED of FIGS. 11A-D showing a process of image enhancement, according tosome embodiments.

FIG. 15 is a flowchart of a method for enhancing images generated by adisplay system or NED like those of FIGS. 11A-D, according to someembodiments.

Throughout the drawings, identical reference characters and descriptionsindicate similar, but not necessarily identical, elements. While theexemplary embodiments described herein are susceptible to variousmodifications and alternative forms, specific embodiments have beenshown by way of example in the drawings and will be described in detailherein. However, the exemplary embodiments described herein are notintended to be limited to the particular forms disclosed. Rather, theinstant disclosure covers all modifications, equivalents, andalternatives falling within the scope of the appended claims.

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

The present disclosure is generally directed to improved NEDs that canbe used in virtual reality (VR) or in augmented or mixed reality(AR/MR). Some NEDs may include a projector device including a firstmonochromatic emitter array having a plurality of emitters of a firstcolor disposed in a two-dimensional configuration and a secondmonochromatic emitter array having a plurality of emitters of a second,different color disposed in a corresponding two-dimensionalconfiguration. These two-dimensional configurations may be identical insome embodiments. The first and second monochromatic emitter arrays maybe configured to emit images of the first and second colors toward acoupling area included in a waveguide configuration having one or morewaveguide members. The waveguide configuration may combine the images toproduce at least one polychromatic image directed toward an eyebox. Insome examples, the waveguide configuration may be configured to projectmultiple replications of the polychromatic image toward the eyebox.

As will be explained in greater detail below, embodiments of the instantdisclosure may provide for NEDs that are smaller and lighter thanconventional NEDs, while still having a large eyebox or eyeboxes and alarge FOV. To provide for less bulky, higher-resolution, and brighternear-eye displays, at least one monochromatic emitter array may becoupled to a waveguide/combiner. The emitter array, in some embodiments,may be a vertical-cavity surface-emitting laser (VCSEL) array or amicroLED array having a high fill factor (e.g., by way of physical oroptical means, such as via microlens or other refractory structures, orreflective structures), which may be close to 100%. In otherembodiments, the emitter array can include other devices (e.g., directemission light sources), including, but not limited to, semiconductordiodes, semiconductor laser diodes, an organic light-emitting diode(OLED) pixel array, a quantum dot array, a liquid-crystal display (LCD)with a variable backlight source, and the like. Projected light mayfirst pass through a very small air gap between the emitter array andthe waveguide before interacting with a coupling element, incorporatedinto the waveguide, that directs the light along a total internalreflection path. The path, in some examples, can include gratingstructures or other types of light decoupling structures that decoupleportions of the light from the total internal reflection path to directmultiple instances of an image, “pupil replications,” out of thewaveguide at different places and toward an eyebox of an HMD.

Red, green, and blue monochromatic emitter arrays may be provided toreproduce full-color images when the respective red, green, and bluemonochromatic images are combined by the waveguide. The emitter arraysmay be coupled to the waveguide by three coupling elements, with onecoupling element specially adapted for each wavelength, to producefull-color images when combined. The colors can be combined in a singlewaveguide or in separate waveguides designed for specific wavelengths,which may prevent crosstalk and allow for per-color optimization of eachof the waveguides and associated gratings that provide for internalreflection and decoupling. Because the emitter arrays are each coupledto the waveguide at different positions, the area of full-colorreplication may be limited to the overlap of all three colors. However,the area of full-color replication may be larger than the eyebox.

In some embodiments, to help resolve the vergence-accommodation conflict(VAC), multiple waveguide/projector display devices can be positioned inseries to present full-color images at different focus distances, suchas at 0.3 diopters (D) and at 1.5 D, to the eye of the user. The displaydevices may be separated by an optical element, such as a lens, toprovide for the different focus distances between each of the twodisplays. To optimize the difference in focus distances for a particularapplication or situation, the individual display devices stacks may beseparated by a variable-focus lens, such as a common liquid or a liquidcrystal lens that can be tuned in situ to achieve a desired differencein focus distance between the display devices.

To increase the FOV of the NED, multiple sets of emitter arrays can becoupled into a single waveguide configuration. For example, one NEDhaving multiple sets of emitter arrays may be used for a user's lefteye, while another NED having multiple sets of emitter arrays may beused for the user's right eye. The sets of emitter arrays for each NEDcan be coupled exactly 180 degrees apart from each other or may becoupled at any other angle relative to each other, in some embodiments,and at different angles with respect to each other in other embodiments.The sets of emitter arrays for each NED may be driven by separatedrivers or controllers or may be driven by a single driver.

To improve resolution or to mitigate defects of individual emitterswithin an emitter array, disclosed systems and devices may include anactuation system that produces changes in relative position and/or anglebetween the emitter array or arrays and the waveguide, or by othermethods described in greater detail below. By mechanically oscillatingor dithering between two or more positions and/or angles, and/or byelectronically shifting pixel locations of the emitted light between twoor more positions on the emitter array itself, a single emitter arraymay act as multiple emitter arrays, projecting a different image ordifferent portion of a single image from each position. In this way,images may have a greater resolution (e.g., a greater two-dimensionalconfiguration of image pixels) than any single emitter array hasemitters. Additionally, embodiments of the emitter arrays may includeindividual emitters having diameters less than or equal to about 5 μm.Because of this small size, producing an emitter array without anyfaulty or defective emitters may be difficult or impossible. Someembodiments may compensate for such faulty emitters by identifying theirlocation or identifying an area or set of emitters that has a lowerbrightness or intensity over a period of time than is instructed whenthe emitter array is in a first position, and actuating a neighboringemitter or set of emitters when the emitter array is in a secondposition, since the second position may cause the neighboring emitter tobe in the location previously occupied by the faulty emitter.Furthermore, in some examples, to mechanically oscillate or dither theemitters, small vibrations (e.g., in the frequency range of 20 Hz to 20kHz) may be introduced to the emitters to compensate for visualartifacts, such as the screen door effect. Examples of mechanisms thatmay be employed to vibrate the emitters may include, but not limited to,one or more piezo structures, actuated liquid-crystal layers, andactuated diffraction gratings.

The following will provide, with reference to FIGS. 1-7D and 9A-14,detailed descriptions of an HMD and various components included in theNEDs of the HMD to achieve the benefits and improvements indicated aboveand elsewhere herein. The following will also provide, with reference toFIGS. 8 and 15, descriptions of methods and/or instructions associatedwith the NEDs described herein.

FIG. 1 is a diagram of a head-mounted display (HMD) 100 according tosome embodiments. The HMD 100 may include a NED, which may include oneor more display devices. The depicted embodiment includes a left displaydevice 110A and a right display device 110B, which are collectivelyreferred to as the display device 110. The display device 110 maypresent media to a user. Examples of media presented by the displaydevice 110 include one or more images, a series of images (e.g., avideo), audio, or some combination thereof. In some embodiments, audiomay be presented via an external device (e.g., speakers and/orheadphones) that receives audio information from the display device 110,a console (not shown), or both, and presents audio data based on theaudio information. The display device 110 may generally be configured tooperate as an AR NED, such that a user can see media projected by thedisplay device 110 and see the real-world environment through thedisplay device 110. However, in some embodiments, the display device 110may be modified to also operate as a VR NED, a mixed reality (MR) NED,or some combination thereof. Accordingly, in some embodiments, thedisplay device 110 may augment views of a physical, real-worldenvironment with computer-generated elements (e.g., images, video,sound, etc.).

The HMD 100 shown in FIG. 1 may include a support or frame 105 thatsecures the display device 110 in place on the head of a user, inembodiments in which the display device 110 includes separate left andright displays. In some embodiments, the frame 105 may be a frame ofeyewear glasses. As is described herein in greater detail, the displaydevice 110, in some examples, may include a waveguide with holographicor volumetric Bragg gratings. In some embodiments, the gratings may begenerated by a process of applying one or more dopants or photosensitivemedia to predetermined portions of the surface of the waveguide andsubsequent ultraviolet (UV) light exposure or application of otheractivating electromagnetic radiation.

FIG. 2 is a cross-section 200 of the HMD 100 and the display device 110Aillustrated in FIG. 1, according to some embodiments. The display device110 may include at least one waveguide configuration 210. FIG. 2 showsan eyebox 230, which is a location where the eye 220 is positioned whenthe user wears the display device 110. As long as the eye 220 is alignedwith the eyebox 230, the user may be able to see a full-color image or apupil replication directed toward the eyebox 230 by the waveguideconfiguration 210. The waveguide configuration 210 may produce anddirect many pupil replications to the eyebox 230. For purposes ofillustration, FIG. 2 shows the cross-section 200 associated with asingle eye 220 and single waveguide configuration 210. In somealternative embodiments, another waveguide configuration 210 (which maybe separate from the waveguide configuration 210 shown in FIG. 2) mayprovide image light to an eyebox located at another eye 220 of the user.

The waveguide configuration 210, as illustrated below in FIG. 2, may beconfigured to direct the image light to an eyebox located proximate tothe eye 220. The waveguide configuration 210 may be composed of one ormore materials (e.g., plastic, glass, etc.) with one or more refractiveindices that effectively minimize the weight and widen an FOV of thedisplay device 110. In alternate configurations, the display device 110may include one or more optical elements between the waveguideconfiguration 210 and the eye 220. The optical elements may act to,e.g., correct aberrations in image light emitted from the waveguideconfiguration 210, magnify image light emitted from the waveguideconfiguration 210, make some other optical adjustment of image lightemitted from the waveguide configuration 210, or perform somecombination thereof. Examples of optical elements may include anaperture, a Fresnel lens, a refractive (e.g., convex and/or concave)lens, a reflective surface, a filter, or any other suitable opticalelement that affects image light. The waveguide configuration 210 mayinclude a waveguide with one or more sets of Bragg gratings.

In some implementations, the lenses described herein can includedifferent designs to meet certain design specifications, including, butnot limited to, a viewing angle, a maximum aperture, a resolution, adistortion, a color correction, a back focal distance, and the like. Thelens or lenses may include a cylindrical lens, an anamorphic lens, aFresnel lens, and/or a gradient index lens, and the like. The lens caninclude a superlens having at least a portion having a negative index ofrefraction. The lens can include lenses having various shapes.

In some implementations, the lens can include various materials. Forexample, the lens may include glass. In another example, the lens caninclude a plastic material. For example, the lens can include a CR-39lens material, a urethane-based polymer, or a polycarbonate material.

FIG. 3 illustrates an isometric view of a display system or NED 300,according to some embodiments. In some embodiments, the NED 300 may be acomponent of the HMD 100. In alternate embodiments, the NED 300 may bepart of another HMD or other system that directs image light to aparticular location.

The NED 300 may include a projector device 310, a waveguide 320, and acontroller 330. For purposes of illustration, FIG. 3 shows the NED 300associated with a single eye 220, but in some embodiments anotherwaveguide that is completely separate or partially separate from the NED300 may provide image light to another eye of the user. In a partiallyseparate system, one or more components may be shared between thewaveguides for each eye. In some instances, a single waveguide 320 mayprovide image light to both eyes of the user. Also, in some examples,the waveguide 320 may be one of multiple waveguides of a waveguideconfiguration, as is described more fully below.

The projector device 310 may generate light including one or moretwo-dimensional monochromatic images. The projector device 310 mayinclude one or more monochromatic optical sources and an optics system,as is further described herein with regard to FIGS. 4A-C and 5A-C. Theprojector device 310 may generate and project image light 355, includingat least one two-dimensional image, to a coupling area 350 located on atop surface 370 of the waveguide 320. The image light 355 may propagatealong a dimension or axis toward the coupling area 350.

The waveguide 320 may be an optical waveguide that outputstwo-dimensional images in image light directed to the eye 220 of a user.The waveguide 320 may receive the image light 355 at a coupling area350, which may include one or more coupling elements located on the topsurface 370 and/or within the body of the waveguide 320, and may guidethe received image light 355 to a propagation area of the waveguide 320.A coupling element of the coupling area 350 may be, e.g., a diffractiongrating, a holographic grating, one or more cascaded reflectors, one ormore prismatic surface elements, an array of holographic reflectors, ametamaterial surface, or some combination thereof. An exemplary couplingelement may be a grating having a pitch of approximately 300 nm toapproximately 600 nm. In some configurations, each of the couplingelements in the coupling area 350 may have substantially the same areaalong the X-axis and the Y-axis dimensions and may be separated by adistance along the Z-axis (e.g., on the top surface 370 and the bottomsurface 380, or both on the top surface 370 but separated by aninterfacial layer (not shown), or on the bottom surface 380 andseparated with an interfacial layer or both embedded into the body ofthe waveguide 320 but separated with the interfacial layer). Thecoupling area 350 may be understood as extending from the top surface370 to the bottom surface 380. The coupling area 350 may redirectreceived image light, according to a first grating vector, into apropagation area of the waveguide 320 formed in the body of thewaveguide 320 between decoupling elements.

A decoupling element 360A may redirect the totally internally reflectedimage light from the waveguide 320 such that it may be decoupled througha decoupling element 360B. The decoupling element 360A may be part of,affixed to, or formed in, the top surface 370 of the waveguide 320. Thedecoupling element 360B may be part of, affixed to, or formed in, thebottom surface 380 of the waveguide 320, such that the decouplingelement 360A is opposed to the decoupling element 360B with apropagation area extending therebetween. In some configurations, theremay be an offset between the opposed decoupling elements along theX-axis and/or Y-axis. The decoupling elements 360A and 360B may be,e.g., a diffraction grating, a holographic grating, a volumetric Bragggrating, one or more cascaded reflectors, one or more prismatic surfaceelements, an array of holographic reflectors, etc., and together mayform a decoupling area.

In some embodiments, each of the decoupling elements 360A may havesubstantially the same area along the X-axis and the Y-axis dimensionsand may be separated by a distance along the Z-axis (e.g., on the topsurface 370 and the bottom surface 380, or both on the top surface 370but separated with an interfacial layer (not shown), or on the bottomsurface 380 and separated with an interfacial layer or both embeddedinto the waveguide body of the waveguide 320 but separated with theinterfacial layer). The decoupling element 360A may have an associatedsecond grating vector, and the decoupling element 360B may have anassociated third grating vector.

While particular locations and configurations of the projector device310, the coupling area 350, and the decoupling elements 360A and 360Brelative to the waveguide 320 are depicted in FIG. 3, other locationsconfigurations described in greater detail below, as well as other notspecifically described herein, may be employed in other examples.

In some embodiments, an orientation and/or position of the image light340 exiting from the waveguide 320 may be controlled by changing anorientation of the image light 355 entering the coupling area 350. Tothat end, in some embodiments, an orientation of the projector device310 relative to the waveguide 320 may alter the orientation and/orposition of the image light 355 entering the coupling area 350. Also, insome examples, an orientation and/or position of one or more opticalcomponents (e.g., lenses) of the projector device 310 relative to amonochromatic emitter array of the projector device 310 may becontrollably modified to alter the orientation and/or position of theimage light 355 entering the coupling area 350. The pitch of thedecoupling element 360A and/or the decoupling element 360B may beapproximately 200 nm to approximately 700 nm. In some configurations,the coupling area 350 couples the image light into the waveguide 320 andthe image light propagates along the plane of the waveguide 320. Thedecoupling element 360A may receive image light from the coupling area350 covering a first portion of the first angular range emitted by theprojector device 310 and may diffract the received image light toanother dimension. The decoupling element 360B may diffract atwo-dimensional expanded image toward the eyebox.

The coupling area 350 and the decoupling area defined by the decouplingelement 360A and the decoupling element 360B may be designed such that asum of their respective grating vectors is less than a threshold value,which may be close to or equal to zero such that light exits thewaveguide 320 at approximately the same angle at which it enters.Accordingly, the image light 355 entering the waveguide 320 may bepropagated in the same direction when it is output as image light 340from the waveguide 320. The image light 340 may include multiple pupilreplications or copies of the input image light 355. The location of thecoupling area 350 relative to the decoupling elements 360A and 360B asshown in FIG. 3 is only an example. In other embodiments, the locationof the coupling area 350 could be on any other portion of the waveguide320 (e.g., a top edge of the top surface 370 or a bottom edge of the topsurface 370). In some embodiments, the NED 300 may include a pluralityof projector devices 310 and/or a plurality of coupling areas 350 toincrease the FOV and/or eyebox further. Also, in some embodiments, thedecoupling elements 360A and 360B may overlap only partially or becompletely separated.

The waveguide 320 may include a waveguide body with the top surface 370and a bottom surface 380, extending in X- and Y-directions, that areopposite to each other. The waveguide 320 may be composed of one or morematerials that facilitate total internal reflection of the image light355. For example, the waveguide 320 may be composed of, e.g., silicone,plastic, glass, ceramics, or polymers, or some combination thereof. Forexample, the waveguide 320 can include a dielectric or other materialthat is substantially transparent in the visible spectrum. An opticalcoating may be used in connection with the waveguide 320. The opticalcoating may be a dielectric coating that can include thin layers ofmaterials such as magnesium fluoride, calcium fluoride, and variousmetal oxides. By choice of the composition, thickness, and number ofthese layers, the reflectivity and transmissivity of the coating can betuned.

The waveguide 320 may have a relatively small form factor. For example,the waveguide 320 may be approximately 50 mm wide along the X-dimension,30 mm long along the Y-dimension, and 0.3-2 mm thick along theZ-dimension. In other embodiments, the waveguide 320 may beapproximately 150 mm wide along the X-dimension and 100 mm long alongthe Y-dimension, with a thickness ranging between 0.1-2 mm along theZ-dimension.

In some embodiments, one or more controllers (such as the controller330) may control the operations of the projector device 310. Thecontroller 330 may generate display instructions for the projectordevice 310. The display instructions may include instructions to projector emit one or more monochromatic images. In some embodiments, displayinstructions may include a monochromatic image file (e.g., bitmap). Thedisplay instructions may be received from, e.g., a processing deviceincluded in the HMD 100 of FIG. 1 or in wireless or wired communicationtherewith. As described herein, the display instructions may furtherinclude instructions for moving the projector device 310, or individualemitter arrays thereof, for moving the waveguide 320 by activating anactuation system. The controller 330 may include a combination ofhardware, software, and/or firmware not explicitly shown herein so asnot to obscure other aspects of the disclosure.

In some embodiments, the waveguide 320 may output the expanded imagelight 340 to the user's eye 220 with a relatively large FOV. Forexample, the expanded image light 340 may be output to the user's eye220 with a diagonal FOV (in X- and Y-directions) of at least 60 degrees.The waveguide 320 may be configured to provide an eyebox with a lengthof at least 20 mm and a width of at least 10 mm, in X- and Y-directions,respectively. Generally, the horizontal FOV may be larger than thevertical FOV. For example, the waveguide 320 may have an aspect ratio of16:9, 16:10, 16:13, or some other aspect ratio.

FIGS. 4A, 4B, and 4C are cross-sectional views of projector devices thatmay be included in the NED 300 of FIG. 3 as the projector device 310,according to some embodiments. The projector device 400A of FIG. 4A mayinclude a plurality of two-dimensional monochromatic emitter arrays. Asshown, the projector device 400A may include a first emitter array 402A,a second emitter array 402B, and a third emitter array 402C, each ofwhich may be disposed in an array housing 404A, 404B, and 404C,respectively. For convenience, the emitter arrays 402A-C may be referredto collectively as emitters arrays 402 and also individually as anemitter array 402. Similarly, the array housings 404A-C may be referredto collectively as housings 404 or individually as a housing 404. Eachof the housings 404 may include an optical system 406, which may includeone or more optical components, such as lenses (e.g., glass, plastic, ormetamaterial lenses), prisms, filters, etc., which may alter thedirection or control other characteristics of light emitted by theemitter arrays 402. As shown, the emitter arrays 402 may be secured to acommon structure, such as an application-specific integrated circuit(ASIC), a printed circuit board (PCB) 408, backplane, or otherstructure, which may include leads that connect the emitter arrays 402to a controller 410. In other embodiments, the controller 410 may bedisposed elsewhere within or on the HMD 100, secured either directly orindirectly to the frame 105.

Each of the emitter arrays 402 may be a monochromatic emitter arrayhaving a two-dimensional configuration of individual emitters of asingle color. As described herein, a green color may be understood as awavelength range from about 500 nm to about 555 nm. Further, asdescribed herein, a red color may be understood as a wavelength rangefrom about 622 nm to about 780 nm. A blue color may be understood as awavelength range from about 440 nm to about 492 nm. Accordingly, amonochromatic emitter array 402 may emit light within a narrowwavelength range, rather than at a single wavelength, in someembodiments. For example, a monochromatic emitter array 402 may emitwithin a wavelength range of 5-10 nm in width, such as by way of usingone or more chromatic filters, which may facilitate a simplifiedprojection lens design with reduced achromatic performance requirements.According to certain examples, the emitter array 402A may include onlyred-light emitters, the emitter array 402B may include only green-lightemitters, and the emitter array 402C may include only blue-lightemitters. Under the direction of the controller 410, each of the emitterarrays 402A-C may produce a monochromatic image according to the colorproduced by its emitters. Accordingly, the three monochromatic emitterarrays 402A-C may simultaneously emit three monochromatic images (e.g.,a red image, a green image, and a blue image) toward the coupling area350 of FIG. 3. The three monochromatic images may be extracted from afull-color image. For example, the controller 410 may receive afull-color image to be displayed to a user and then decompose thefull-color into multiple monochromatic images, such a red image, a greenimage, and a blue image. As described herein, the waveguideconfiguration 320 may combine (or recombine) the three monochromaticimages to produce a full-color image or a polychromatic image, which maythen be directed as the light 340 toward the eye 220. In yet otherexamples, one or more emitter arrays 402A-C may produce light ofmultiple wavelengths, ranges of wavelengths, or other forms of lightother than monochromatic light.

In some embodiments, a calibration and/or alignment system (not shown inFIG. 4A) may be employed to align the multiple monochromatic images(e.g., via mechanical movement of one or more of the monochromaticemitter arrays 402A-C or software movement of one or more of themonochromatic images by one or more pixels as emitted from theirassociated monochromatic emitter arrays 402A-C) to produce a desired orintended, properly aligned polychromatic image.

FIG. 4B depicts a projector device 400B in which a plurality of emitterarrays may not be fixed with respect to each other by being secured to acommon ASIC, PCB, backplane, or other structure. Instead, each of theemitter arrays 402 may be secured to an individual PCB 408A, 408B, 408C,and 408D. In other embodiments, ASICs or other individual structures, orsome combination thereof, may be employed in place of one or more of thePCBs 408A-D. The projector device 400B may include a fourthmonochromatic emitter array 402D (or other emitter array emitting lightthat is not strictly monochromatic) disposed within a fourth arrayhousing 404D. In some embodiments, the emitter array 402D may be awhite-light emitter array, such that each emitter of the emitter array402D produces only white light. In some embodiments, the white-lightemitter array may be used to produce white image pixels that wouldotherwise be produced by a combination of the emitter arrays 402A-C. Thewhite-light emitter array may produce light that is perceived by aviewer as white. In some embodiments, the white-light emitter array mayinclude blue microLEDs with a yellow phosphor coating (e.g.,Cerium(III)-doped yttrium aluminum garnet (Ce:YAG)). The combination ofthe blue emitters and the phosphor may provide light that appears whiteto the user. This may reduce power consumption by substituting the powerrequirements of a single emitter array for a combination ofthree-emitter arrays. Additionally or alternatively, such amonochromatic image produced by the emitter array 402D may be abrightness or saturation image that does not substantially alter thecolors of the polychromatic image produced by combining the three imagesfor the emitter arrays 402A-C. In some embodiments, the white-lightemitter array may be a micro-OLED emitter array that produces a broadvisible emission spectrum that may be perceived as white. In otherexamples, the fourth monochromatic emitter array 402D may emit anothercolor (e.g., cyan or other color between green and blue) may be moreefficient overall, and may facilitate use of the monochromatic emitterarrays 402A-D as a four-color primary system.

FIG. 4C depicts a projector device 400C in which a height of the emitterarrays 402 may vary from emitter array to emitter array. As shown, thearray housing 404A may be higher or taller than the array housing 404B,which in turn may be higher or taller than the array housing 404C. Thedifferences in height may permit differences in the optical systemincluded in each housing. Accordingly, the optical system 406A may havemore or larger components or may operate at a higher power level thanthe optical system 406B, which in turn may have more components and/or alower power level than the optical system 406C. For example, the emitterarray 402A of FIG. 4C may be a green image emitter array. The largersize of the green emitter array 402A may provide for greater heatdissipation and/or improved optics. This may enable the green image tobe the brightest of the three monochromatic images.

FIGS. 5A, 5B, and 5C are top views of emitter array configurations thatmay be included in the projector device 310 of FIG. 3, according to someembodiments. The configuration 500A shown in FIG. 5A is a linearconfiguration of the emitter arrays 402A-C of FIG. 4A along the axis A1.This particular linear configuration may be arranged according to alonger side of the rectangular emitter arrays 402. While the emitterarrays 402 may have a square configuration of emitters in someembodiments, other embodiments may include a rectangular configurationof emitters. In yet other examples, the emitter arrays 402A-C may haveother configurations (e.g., oval, circular, or otherwise rounded in somefashion) while defining a first dimension (e.g., a width) and a seconddimension (e.g., length) orthogonal to the first direction, with onedimension being either equal or unequal to each other. In FIG. 5B, theemitter arrays 402A-C may be disposed in a linear configuration 500Baccording to a shorter side of the rectangular emitter arrays 402, alongan axis A2. FIG. 5C shows a triangular configuration of the emitterarrays 402A-C in which the centers of the emitter arrays 402 form anon-linear (e.g., triangular) shape or configuration. Some embodimentsof the configuration 500C of FIG. 5C may further include a white-lightemitter array 402D, such that the emitter arrays 402 are in arectangular or square configuration. The emitter arrays 402 may have atwo-dimensional emitter configuration with more than 1000 by 1000emitters, in some embodiments. Various other configurations are alsowithin the scope of the present disclosure.

FIGS. 6A and 6B are schematic cross-sectional diagrams of an examplemicroLED 600A that may be included as an individual emitter in theemitter arrays 402 of FIGS. 4A-C and 5A-C, according to someembodiments. FIG. 6A shows a schematic cross-section of a microLED 600A.A “microLED” may be a particular type of LED having a small active lightemitting area (e.g., less than 2,000 μm² in some embodiments, less than20 μm² or less than 10 μm² in other embodiments). In some embodiments,the emissive surface of the microLED 600A may have a diameter of lessthan approximately 5 μm, although smaller (e.g., 2 μm) or largerdiameters for the emissive surface may be utilized in other embodiments.The microLED 600A may also have collimated or non-Lambertian lightoutput, in some examples, which may increase the brightness level oflight emitted from a small active light-emitting area.

The microLED 600A may include, among other components, an LED substrate602 with a semiconductor epitaxial layer 604 disposed on the substrate602, a dielectric layer 614 and a p-contact 619 disposed on theepitaxial layer 604, a metal reflector layer 616 disposed on thedielectric layer 614 and p-contact 619, and an n-contact 618 disposed onthe epitaxial layer 604. The epitaxial layer 604 may be shaped into amesa 606. An active light-emitting area 608 may be formed in thestructure of the mesa 606 by way of a p-doped region 617 of theepitaxial layer 604.

The substrate 602 may include transparent materials such as sapphire orglass. In one embodiment, the substrate 602 may include silicon, siliconoxide, silicon dioxide, aluminum oxide, sapphire, an alloy of siliconand germanium, indium phosphide (InP), and the like. In someembodiments, the substrate 602 may include a semiconductor material(e.g., monocrystalline silicon, germanium, silicon germanium (SiGe),and/or a III-V based material (e.g., gallium arsenide), or anycombination thereof. In various embodiments, the substrate 602 caninclude a polymer-based substrate, glass, or any other bendablesubstrate including two-dimensional materials (e.g., graphene andmolybdenum disulfide), organic materials (e.g., pentacene), transparentoxides (e.g., indium gallium zinc oxide (IGZO)), polycrystalline III-Vmaterials, polycrystalline germanium, polycrystalline silicon, amorphousIII-V materials, amorphous germanium, amorphous silicon, or anycombination thereof. In some embodiments, the substrate 602 may includea III-V compound semiconductor of the same type as the active LED (e.g.,gallium nitride). In other examples, the substrate 602 may include amaterial having a lattice constant close to that of the epitaxial layer604.

The epitaxial layer 604 may include gallium nitride (GaN) or galliumarsenide (GaAs). The active layer 608 may include indium gallium nitride(InGaN). The type and structure of semiconductor material used may varyto produce microLEDs that emit specific colors. In one embodiment, thesemiconductor materials used can include a III-V semiconductor material.III-V semiconductor material layers can include those materials that areformed by combining group III elements (Al, Ga, In, etc.) with group Velements (N, P, As, Sb, etc.). The p-contact 619 and n-contact 618 maybe contact layers formed from indium tin oxide (ITO) or anotherconductive material that can be transparent at the desired thickness orarrayed in a grid-like pattern to provide for both good opticaltransmission/transparency and electrical contact, which may result inthe microLED 600A also being transparent or substantially transparent.In such examples, the metal reflector layer 616 may be omitted. In otherembodiments, the p-contact 619 and the n-contact 618 may include contactlayers formed from conductive material (e.g., metals) that may not beoptically transmissive or transparent, depending on pixel design.

In some implementations, alternatives to ITO can be used, includingwider-spectrum transparent conductive oxides (TCOs), conductivepolymers, metal grids, carbon nanotubes (CNT), graphene, nanowiremeshes, and thin-metal films. Additional TCOs can include doped binarycompounds, such as aluminum-doped zinc-oxide (AZO) and indium-dopedcadmium-oxide. Additional TCOs may include barium stannate and metaloxides, such as strontium vanadate and calcium vanadate. In someimplementations, conductive polymers can be used. For example, apoly(3,4-ethylenedioxythiophene) PEDOT: poly(styrene sulfonate) PSSlayer can be used. In another example, a poly(4,4-dioctylcyclopentadithiophene) material doped with iodine or2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) can be used. The examplepolymers and similar materials can be spin-coated in some exampleembodiments.

In some embodiments, the p-contact 619 may be of a material that formsan ohmic contact with the p-doped region 617 of the mesa 606. Examinerof such materials may include, but are not limited to, palladium, nickeloxide deposited as a NiAu multilayer coating with subsequent oxidationand annealing, silver, nickel oxide/silver, gold/zinc, platinum gold, orother combinations that form ohmic contacts with p-doped III-Vsemiconductor material.

The mesa 606 of the epitaxial layer 604 may have a truncated top on aside opposed to a substrate light emissive surface 610 of the substrate602. The mesa 606 may also have a parabolic or near-parabolic shape toform a reflective enclosure or parabolic reflector for light generatedwithin the microLED 600A. However, while FIG. 6A depicts a parabolic ornear-parabolic shape for the mesa 606, other shapes for the mesa 606 arepossible in other embodiments. The arrows indicate how light 612 emittedfrom the active layer 608 may be reflected off the internal walls of themesa 606 toward the light emissive surface 610 at an angle sufficientfor the light to escape the microLED 600A (i.e., outside an angle oftotal internal reflection). The p-contact 619 and the n-contact 618 mayelectrically connect the microLED 600A to a substrate.

The parabolic-shaped structure of the microLED 600A may result in anincrease in the extraction efficiency of the microLED 600A into lowillumination angles when compared to unshaped or standard LEDs. StandardLED dies may generally provide an emission full width at half maximum(FWHM) angle of 120°. In comparison, the microLED 600A can be designedto provide controlled emission angle FWHM of less than standard LEDdies, such as around 60°. This increased efficiency and collimatedoutput of the microLED 600A can enable improvement in overall powerefficiency of the NED, which can be important for thermal managementand/or battery life.

The microLED 600A may include a circular cross-section when cut along ahorizontal plane, as shown in FIG. 6A. However, the microLED 600Across-section may be non-circular in other examples. The microLED 600Amay have a parabolic structure etched directly onto the LED die duringthe wafer processing steps. The parabolic structure may include theactive light-emitting area 608 of the microLED 600A to generate light,and the parabolic structure may reflect a portion of the generated lightto form the quasi-collimated light 612 emitted from the substrate lightemissive surface 610. In some examples, the optical size of the microLED600A may be smaller than or equal to the active light-emitting area 608.In other embodiments, the optical size of the microLED 600A may belarger than the active light-emitting area 608, such as through arefractive or reflective approach, to improve usable brightness of themicroLED 600A, including any chief ray angle (CRA) offsets to beproduced by the emitter array 402.

FIG. 6B depicts a microLED 600B that is similar in many respects to themicroLED 600A of FIG. 6A. The microLED 600B may further include amicrolens 620, which may be formed over the parabolic structure. In someembodiments, the microlens 620 may be formed by applying a polymercoating over the microLED 600A, patterning the coating, and reflowingthe coating to achieve the desired lens curvature. The microlens 620 maybe disposed over an emissive surface to alter a chief ray angle of themicroLED 600B. In another embodiment, the microlens 620 may be formed bydepositing a microlens material above the microLED 600A (for example, bya spin-on method or a deposition process). For example, a microlenstemplate (not shown) having a curved upper surface can be patternedabove the microlens material. In some embodiments, the microlenstemplate may include a photoresist material exposed using a distributingexposing light dose (e.g., for a negative photoresist, more light isexposed at a bottom of the curvature and less light is exposed at a topof the curvature), developed, and baked to form a rounding shape. Themicrolens 620 can then be formed by selectively etching the microlensmaterial according to the microlens template. In some embodiments, theshape of the microlens 620 may be formed by etching into the substrate602. In other embodiments, other types of light-shaping orlight-distributing elements, such as an annular lens, Fresnel lens, orphotonic crystal structures, may be used instead of microlenses.

In some embodiments, microLED arrangements other than those specificallydiscussed above in conjunction with FIGS. 6A and 6B may be employed as amicroLED in emitter array 402. For example, the microLED may includeisolated pillars of epitaxially grown light-emitting material surroundedby a metal reflector. The pixels of the emitter array 402 may alsoinclude clusters of small pillars (e.g., nanowires) of epitaxially grownmaterial that may or may not be surrounded by reflecting material orabsorbing material to prevent optical crosstalk. In some examples, themicroLED pixels may be individual metal p-contacts on a planar,epitaxially grown LED device, in which the individual pixels may beelectrically isolated using passivation means, such as plasma treatment,ion-implantation, or the like. Such devices may be fabricated with lightextraction enhancement methods, such as microlenses, diffractivestructures, or photonic crystals. Other processes for fabricating themicroLEDs of the dimensions noted above other than those specificallydisclosed herein may be employed in other embodiments.

FIGS. 7A, 7B, 7C, and 7D are cross-sectional views of display systems orNEDs that include a projector device and a waveguide configuration,according to some embodiments. The embodiments depicted in FIGS. 7A-Dmay provide for the projection of many image replications (e.g., pupilreplications), while other embodiments may instead provide fordecoupling a single image projection at a single point. Accordingly,additional embodiments of disclosed NEDs may provide for a singledecoupling element. Outputting a single image toward the eyebox 230 maypreserve the intensity of the coupled image light. Some embodiments thatprovide for decoupling at a single point may further provide forsteering of the output image light. Such pupil-steering NEDs may furtherinclude systems for eye tracking to monitor a user's gaze. Someembodiments of the waveguide configurations that provide for pupilreplication, as described herein, may provide for one-dimensionalreplication, while other embodiments may provide for two-dimensionalreplication. As illustrated in FIGS. 7A-D, two-dimensional pupilreplication may include directing light into and outside the plane ofeach figure. The figures are presented in a simplified format. Thedetected gaze of the user may be used to adjust the position and/ororientation of the emitter arrays individually or the projector device750 as a whole and/or to adjust the position and/or orientation of thewaveguide configuration. Some exemplary actuation systems for adjustingposition and/or orientation of display system components to steer anoutput image pupil are described in greater detail below with respect toFIGS. 11A-D.

In FIG. 7A, a waveguide configuration 700A is disposed in cooperationwith a projector device 750, which may include one or more monochromaticemitters 752 secured to a support structure 754 (e.g., a printed circuitboard or another structure). The support structure 754 may be coupled tothe frame 105 of FIG. 1. The waveguide configuration 700A may beseparated from the projector device 750 by an air gap having a distanceD1. The distance D1 may be in a range from approximately 50 μm toapproximately 500 μm in some examples. The monochromatic image or imagesprojected from the projector device 750 may pass through the air gaptoward the waveguide configuration 700A. Any of the projector deviceembodiments described herein may be utilized as the projector device750.

The waveguide configuration 700A may include a waveguide 702A, which maybe formed from a glass or plastic material. The waveguide 702A mayinclude a coupling area 704A and a decoupling area formed by decouplingelements 706A on a top surface 708A and decoupling elements 706B on abottom surface 708B in some embodiments. The area within the waveguide702A in between the decoupling elements 706A and 706B may be considereda propagation area 710, in which light images received from theprojector device 750 and coupled into the waveguide 702A by couplingelements included in the coupling area 704A may propagate laterallywithin the waveguide 702A.

The coupling area 704A may include a coupling element 712 configured anddimensioned to couple light of a predetermined wavelength, e.g., red,green, or blue light. When a white light emitter array is included inthe projector device 750, the portion of the white light that falls inthe predetermined wavelength may be coupled by each of the couplingelements 712. In some embodiments, the coupling elements 712 may begratings, such as Bragg gratings, dimensioned to couple a predeterminedwavelength of light. In some examples, the gratings of each couplingelement 712 may exhibit a separation distance between gratingsassociated with the predetermined wavelength of light that theparticular coupling element 712 is to couple into the waveguide 702A,resulting in different grating separation distances for each couplingelement 712. Accordingly, each coupling element 712 may couple a limitedportion of the white light from the white light emitter array whenincluded. In other examples, the grating separation distance may be thesame for each coupling element 712. In some examples, coupling element712 may be or include a multiplexed coupler.

As shown in FIG. 7A, a red image 720A, a blue image 7206, and a greenimage 720C may be coupled by the coupling elements of the coupling area704A into the propagation area 710 and may begin traversing laterallywithin the waveguide 702A. A portion of the light may be projected outof the waveguide 702A after the light contacts the decoupling element706A for one-dimensional pupil replication, and after the light contactsboth the decoupling element 706A and the decoupling element 706B fortwo-dimensional pupil replication. In two-dimensional pupil replicationembodiments, the light may be projected out of the waveguide 702A atlocations where the pattern of the decoupling element 706A intersectsthe pattern of the decoupling element 706B.

The portion of light that is not projected out of the waveguide 702A bythe decoupling element 706A may be reflected off the decoupling element706B. The decoupling element 706B may reflect all incident light backtoward the decoupling element 706A, as depicted. Accordingly, thewaveguide 702A may combine the red image 720A, the blue image 7206, andthe green image 720C into a polychromatic image instance, which may bereferred to as a pupil replication 722. The polychromatic pupilreplication 722 may be projected toward the eyebox 230 of FIG. 2 and tothe eye 220, which may interpret the pupil replication 722 as afull-color image (e.g., an image including colors in addition to red,green, and blue). The waveguide 702A may produce tens or hundreds ofpupil replications 722 or may produce a single replication 722.

FIG. 7B is a cross-sectional view of a waveguide configuration 700B andthe projector device 750. The waveguide configuration 700B may besimilar to the waveguide configuration 700A of FIG. 7A in many respects.The waveguide configuration 700B may differ from the waveguideconfiguration 700A in that the waveguide 702B may include a differentcoupling area 704B. Rather than include gratings as coupling elements712, the coupling area 704B of the waveguide configuration 700B mayinclude a prism, extending inwardly from the bottom surface 708B, thatreflects and refracts received image light, directing it toward thedecoupling element 706A. Similarly, FIG. 7C is a cross-sectional view ofa waveguide configuration 700C and the projector device 750. Thewaveguide configuration 700C may also include many of the featuresdescribed herein in connection with the waveguide configuration 700A ofFIG. 7A. The waveguide configuration 700C may include a waveguide 702Chaving a coupling area 704C with a prismatic element that protrudesupwardly from the top surface 708A.

FIG. 7D is a cross-sectional view of a waveguide configuration 700D anda projector device 760. The waveguide configuration 700D may includemultiple waveguides. As shown, a set of waveguides 702D may include afirst waveguide 730A, a second waveguide 730B, and a third waveguide730C. Each of the waveguides 730 may include its own coupling area 732A,732B, and 732C, respectively. Each of the coupling areas 732 may beadapted to receive a predetermined wavelength of light. Similarly, eachof the waveguides 730 may be adapted to receive a predeterminedwavelength of light by having a predetermined thickness based on thewavelength of light, for example. Other optical properties of thewaveguides 730 may be adapted based on the predetermined wavelength oflight the waveguide is to receive. Each of the waveguides 730 may havedecoupling areas that may also be specifically adapted for thepredetermined wavelength of light. The decoupling elements 706A and 706Bhave not been explicitly depicted in FIG. 7D for clarity.

Like the projector device 400C of FIG. 4C, the projector device 760 mayinclude array housings of different lengths for different colors. Asshown, the array housing 762A may be longer than the array housing 762B,which in turn may be longer than the array housing 762C. The height orbarrel length associated with each individual emitter array of theprojector device 760 may allow for improved optics, increased heatdissipation, etc. As noted herein, the tallest array housing 762A mayinclude an emitter array that emits green light or green images, becausehuman eyes are most responsive to green light wavelengths. When using astacked waveguide configuration, like the waveguide configuration 700D,each waveguide 730 should accommodate each other waveguide. For example,the waveguide 730A may pass (1) the image 720B, which may be projectedby the waveguide 730B, and (2) the image 720C, which may be projected bythe waveguide 730C. Similarly, the waveguide 730B may pass the image720C, which may be projected by the waveguide 730C. In this way, thepupil replication 722 may include the visually aligned and overlappingimages 720A, 720B, and 720C.

Because the barrel of the array housing 762A may extend from above a topsurface of the waveguide 730C to a bottom surface of the waveguide 730B,both the waveguide 730C and the waveguide 730B may be shaped orconfigured to accommodate the housing 762A. For example, a notch orcutout may be formed in the waveguide 730B to accommodate the arrayhousing 762A. Similarly, a notch or cutout may be formed in thewaveguide 730C to accommodate both the array housing 762A and the arrayhousing 762B. The waveguide 730A may not require any cutout because noarray housing may extend beyond the top surface of the waveguide 730A.

While FIGS. 7A-D illustrate various waveguide configurations 700A-700Dthat may be employed in conjunction with various monochromatic emitterarrays discussed herein, other waveguide configurations not specificallydisclosed herein that receive light from monochromatic emitter arrays(e.g., monochromatic emitter arrays 402A-D) and combine that light toproduce a polychromatic image may also be employed in other embodiments.For example, while FIGS. 7A-D generally show the projector device 750having multiple monochromatic emitters 752 coupled to the same supportstructure 754, other embodiments may employ a projector device 750 withseparate monochromatic emitters 752 located at disparate locations aboutthe waveguide configuration 700 (e.g., one or more monochromaticemitters 752 located near a top surface of the waveguide configuration700 and one or more monochromatic emitters 752 located near a bottomsurface of the waveguide configuration 700).

FIG. 8 is a flowchart of a method 800 of displaying an image in adisplay system or NED like those shown in FIGS. 7A-D, according to someembodiments. One or more of the steps shown in FIG. 8 may be performedby any suitable computer-executable code and/or computing system,including the system(s) illustrated in FIGS. 1, 2, 3, etc. For example,one or more of the steps may be performed by the controller 330 of FIG.3 or other processing devices described herein. In one example, each ofthe steps shown in FIG. 8 may represent an algorithm whose structureincludes and/or is represented by multiple sub-steps, examples of whichwill be provided in greater detail below. Embodiments of the method 800may include additional steps before, after, in between, or as part ofthe enumerated steps shown in FIG. 8.

As illustrated in FIG. 8, at a step 802, a processing device may causeemission of a first monochromatic image from a first monochromaticemitter array toward a first coupling element of a waveguide. Forexample, the controller 330 may direct the monochromatic emitter array402A of the projector device 400A of FIG. 4A to emit a firstmonochromatic image. In this example, the monochromatic image may be animage consisting of red light. The monochromatic image may be directedto a coupling element 712 included in the coupling area 704A of thewaveguide configuration 700A of FIG. 7A. In some embodiments, theprocessing device, such as the controller 330 or another processingdevice, may direct the decomposition or may decompose a full-color imageto a plurality of monochromatic images including the first monochromaticimage.

At a step 804, the processing device may direct emission of a secondmonochromatic image from a second monochromatic emitter array toward asecond coupling element of the waveguide. For example, the controller330 may cause the monochromatic emitter array 402B of the projectordevice 400A of FIG. 4A to emit the second monochromatic image, which maybe a monochromatic image consisting of blue light. The blue lightmonochromatic image may be projected to a corresponding coupling element712 of the waveguide configuration 700A.

As a result of steps 802 and 804, a polychromatic image may be directedor projected from a decoupling element of the waveguide, with thepolychromatic image being a combination of the first and secondmonochromatic images. For example, a polychromatic image may be providedin the pupil replication 722 of FIG. 7A, which may combine themonochromatic images 720A, 720B, and 720C into a single full-colorimage, which may be projected by the decoupling elements 706A toward aneyebox 230 and therethrough to the eye 220 of a user. The projection ofthe polychromatic image may be a consequence of the processing devicedirection emission of the first and second monochromatic images into thewaveguide and of the optical features of the waveguide itself.

Some embodiments of the method 800 may result in replicating apolychromatic image to produce a plurality of instances of thepolychromatic image within the waveguide, in which projecting thepolychromatic image from the decoupling element of the waveguide mayinclude projecting the plurality of instances of the polychromatic imagefrom the decoupling element. For example, the waveguide 702A may producea plurality of pupil replications like the pupil replication 722.

In some additional embodiments of the method 800, the first couplingelement may receive the emitted first monochromatic image on a firstsurface of the waveguide and the decoupling element may project thepolychromatic image toward an eyebox from a second surface of thewaveguide, with the second surface being disposed opposite the firstsurface. For example, the coupling element 712 may receive the image720A through a top surface 708A of the waveguide 702A. The pupilreplications 722 may be emitted through the bottom surface 708B.

Additionally, some embodiments of the method 800 may include a step ofdirecting emission of a white-light monochromatic image from amonochromatic emitter array by activating a plurality of LEDs that emitwhite light. For example, the monochromatic emitter array 402D of FIG.4B may include white light emitters that can be activated to produce awhite light image.

Also, in some embodiments of the method 800, the controller 330 mayreceive a signal representing a polychromatic or “white-light” image,which the controller 330 may decompose in constituent colors of a colorspace, where each of the constituent colors defines the monochromaticimage to be produced by each monochromatic emitter array 402A-D.Additionally, some embodiments of the method 800 may include a tangible,non-transitory computer-readable medium having instructionscorresponding to one or more of the described steps or operations of themethod 800 stored thereon. When a processing device executes theinstructions, the processing device may perform one or more of the stepsof the method 800.

FIGS. 9A, 9B, and 9C are perspective views of display systems or NEDs,according to some embodiments. The NED 900A in FIG. 9A may include anelongate waveguide configuration 902 that may be wide or long enough toproject images to both eyes of a user. The waveguide configuration 902may include a decoupling area 904. In order to provide images to botheyes of the user through the waveguide configuration 902, multiplecoupling areas 906 may be provided in a top surface of the waveguide ofthe waveguide configuration 902. The coupling areas 906A and 906B mayinclude multiple coupling elements to interface with light imagesprovided by an emitter array set 908A and an emitter array set 908B,respectively. Each of the emitter array sets 908 may include a pluralityof monochromatic emitter arrays, as described herein. As shown, theemitter array sets 908 may each include a red emitter array, a greenemitter array, and a blue emitter array. As described herein, someemitter array sets may further include a white emitter array or anemitter array emitting some other color or combination of colors.

In some implementations of the waveguide configuration 902, the emitterarray sets 908 may cover approximately identical portions of thedecoupling area 904, as shown by the divider line 910A. In otherembodiments, the emitter array sets 908 may provide images into thewaveguide of the waveguide configuration 902 asymmetrically, as shown bythe divider line 910B. In such an implementation, the emitter array set908A may provide images to more than half of the decoupling area 904,while the emitter array set 908B may provide images to less than half ofthe decoupling area 904. While the emitter array sets 908 may bedisposed at opposite sides of the waveguide configuration 902 as shownin FIG. 9A, other embodiments may include emitter array sets 908arranged at angles other than 180° apart. While the waveguideconfiguration 902 may be planar in some embodiments, it may also have acurved cross-sectional shape in other embodiments to better conform tothe face/head of a user.

FIG. 9B is a perspective view of an NED 900B that has a waveguideconfiguration with a right eye waveguide 920A and a left eye waveguide920B with decoupling areas 922A and 922B, respectively. The right eyewaveguide 920A may include one or more coupling areas 924A, 924B, 924C,and 924D (all or a portion of which may be referred to collectively ascoupling areas 924) and a corresponding number of emitter array sets926A, 926B, 926C, and 926D (all or a portion of which may be referred tocollectively as the emitter array sets 926). Accordingly, while thedepicted embodiment of the right eye waveguide 920A may include twocoupling areas 924 and two emitter array sets 926, other embodiments mayinclude more or fewer. In some embodiments, the individual emitterarrays of an emitter array set may be disposed at different locationsaround a decoupling area. For example, the emitter array set 926A mayinclude a red emitter array disposed along a left side of the decouplingarea 922A, a green emitter array disposed along the top side of thedecoupling area 922A, and a blue emitter array disposed along the rightside of the decoupling area 922A. Accordingly, emitter arrays of anemitter array set may be disposed all together, in pairs, orindividually, relative to a decoupling area.

The left eye waveguide 920B may include the same number andconfiguration of coupling areas 924 and emitter array sets 926 as theright eye waveguide 920A, in some embodiments. In other embodiments, theleft eye waveguide 920B and the right eye waveguide 920A may includedifferent numbers and configurations (e.g., positions and orientations)of coupling areas 924 and emitter array sets 926. Included in thedepiction of the right eye waveguide 920A is a depiction of theeffective pupil replication areas of the individual emitter arraysincluded in one emitter array set 926. For example, a red emitter arrayof the emitter array set 926 may produce pupil replications of a redimage within the limited area 928A. A green emitter array may producepupil replications of a green image within the limited area 928B. A blueemitter array may produce pupil replications of a blue image within thelimited area 928C. Because the limited areas 928 may be different fromone monochromatic emitter array to another, only the overlappingportions of the limited areas 928 may be able to provide full-colorpupil replication, projected toward the eyebox 230.

FIG. 9C is a perspective view of an NED 900C that is similar to the NEDs900A and 900B of FIGS. 9A and 9B in certain respects. The NED 900C mayinclude a waveguide configuration that has a first waveguide portion940A with a coupling area 944A and a second waveguide portion 940B witha coupling area 944B. As shown, waveguide portions 940A and 940B may beconnected by a bridge waveguide 940C and may have decoupling areas 942Aand 942B. The bridge waveguide 940C may permit light from the emitterarray set 946A to propagate from the waveguide portion 940A into thewaveguide portion 940B. Similarly, the bridge waveguide 940C may permitlight emitted from the emitter array set 946B to propagate from thewaveguide portion 940B into the waveguide portion 940A. In someembodiments, the bridge waveguide portion 940C may not include anydecoupling elements, such that all light totally internally reflectswithin the waveguide portion 940C. In other embodiments, the bridgewaveguide portion 940C may include a decoupling area 942C. In someembodiments, the bridge waveguide 940C may be used to obtain light fromboth waveguide portions 940A and 940B and couple the obtained light to adetection (e.g. a photodetector), such as to detect image misalignmentbetween the waveguide portions 940A and 940B.

FIG. 10A is a perspective view of another display system or NED 1000A,which has a multi-planar waveguide configuration 1002, according to someembodiments. As shown, the waveguide configuration 1002 may include afirst waveguide portion 1004A and a second waveguide portion 1004B. Thefirst and second waveguide portions 1004A and 1004B may be substantiallycoplanar and present images to a user on a first image plane. The firstwaveguide portion 1004A may include a coupling area 1006A and adecoupling area 1008A. The second waveguide portion 1004B may include acoupling area 1006B and a decoupling area 1008B. An emitter array set1010A may be aligned with the coupling area 1006A and an emitter arrayset 10106 may be aligned with the coupling area 1006B.

The waveguide configuration 1002 may provide for a second image plane byinclusion of the third waveguide portion 1004C and the fourth waveguideportion 1004D. The third waveguide portion 1004C and the fourthwaveguide portion 1004D may be connected by a bridge waveguide portion1004E, such that decoupling areas 1008C, 1008D, and 1008E may define aunified propagation area for a second image plane. The third waveguideportion 1004C may include multiple coupling areas, of which the couplingarea 1006C is visible in FIG. 10A. The fourth waveguide portion 1004Dmay include coupling areas 1006D and 1006E. Each of the coupling areas1006C-E may have an associated emitter array set 1010C, 1010D, and1010E, respectively. The waveguide configuration 1002 may provide fortwo image planes, such that the user may perceive projected images to bepositioned at different depths.

FIG. 10B is a cross-sectional view of the display system or NED 1000B,according to some embodiments. Like the NED 1000A of FIG. 10A, the NED1000B may provide for multiple image planes. In the embodiment of theNED 1000B shown in FIG. 10B, the first image plane may be provided bythe waveguide configuration 1050A, which may include three waveguides1052A, 1052B, and 1052C for each of the three monochromatic emitterarrays included in the first projector device 1054A. The second imageplane may be provided by the waveguide configuration 1050B, which mayalso include three waveguides 1052D, 1052E, and 1052F. The waveguides1052A-F may be similar to other waveguides described herein, such asthose depicted in FIGS. 7A-D. A second projector device 1054B mayinclude three or more monochromatic emitter arrays as described herein.As noted, some embodiments of the present disclosure may permit a userto visualize information displayed by the waveguide configurations 1050Aand 1050B while also visualizing a surrounding environment 1060 throughthe configurations 1050A and 1050B.

Embodiments of the NED 1000B may include optical components in additionto the waveguide configurations 1050A and 1050B. For example, an opticalcomponent 1062 may be disposed in between the waveguide configurations1050A and 1050B. The optical component 1062 may be a lens or otheroptical component that can produce an apparent separation distancebetween the two image planes. For example, the optical component 1062may be a −0.5 diopter (D) lens. In some embodiments, the opticalcomponent 1062 may be a variable focus component, such as anelectrically-tunable liquid crystal lens or another variable-focus lensthat can be adjusted by a controller, like the controller 330 of FIG. 3,using electrostatic, thermal, or mechanical actuators. The apparentseparation distance, in diopter space, introduced by the opticalcomponent 1062 may range from approximately 0.3 D to approximately 1.5D, in some embodiments. Additional optical components 1064 and 1066 maybe included in some embodiments of the NED 1000B to improve performance.The optical components 1064 and/or 1066 may have fixed or variable focallengths. The optical components 1062, 1064, and 1066 may be calibratedand operated such that the total lens effect sums to zero, so thatlittle or no optical distortion of the surrounding environment 1060 isproduced.

Embodiments as shown in FIGS. 10A and 10B, as well as others notspecifically discussed above that may present multiple image planes to aviewer, may be employed to address the VAC problem mentioned above, thuspotentially providing a more realistic and/or pleasing viewerexperience.

FIGS. 11A, 11B, and 11C are cross-sectional views of display systemshaving an actuation system, according to some embodiments. The displaysystem 1100 of FIG. 11A may include a projector device 1102 and awaveguide configuration 1104. In some embodiments, either or both theprojector device 1102 and the waveguide configuration 1104 may becoupled to the frame 105 of the HMD 100 of FIG. 1 by actuationcomponents. The waveguide configuration 1104 and/or the projector device1102 may be disposed within slots that ensure a parallel or otherwisefixed relationship in one dimension. The slots may prevent the projectordevice 1102 and/or the waveguide configuration 1104 may being disposedin a cantilevered configuration. For example, the projector device 1102may be coupled to the frame 105 by an actuation component 1106A and by afirst slot, while, additionally or alternatively, the waveguideconfiguration 1104 may be coupled to the frame 105 by an actuationcomponent 1106B and a second slot.

In some embodiments, the actuation components 1106A and/or 1106B may beactivated by the controller 330 of FIG. 3 or another processing devicethat operates as part of an actuation system. The actuation components1106A and/or 1106B may be provided by a piezoelectric element, a voicecoil motor, or another suitable actuation component that can dither oroscillate (e.g., move between at least a first position and a secondposition, such as between a first pixel position and an adjacent secondpixel position, as perceived by the user) rapidly. For example, theactuation components 1106A and 1106B may be operated at an integermultiple of a frame rate of images to be provided to the user. Forexample, if the image frame rate is 60 Hz, the actuation system mayoperate at 120 Hz or at 180 Hz.

As shown in FIG. 11B, activation of the actuation component 1106A maycause displacement of the projector device 1102 relative to the frame105 and/or the waveguide configuration 1104. The displacement may have amagnitude of displacement D2 in a first direction, such as theX-direction. In some embodiments, the actuation components 1106A and1106B may operate along a single dimension. In other embodiments, theactuation components 1106A and 1106B may permit the projector device1102 and/or the waveguide configuration 1104 to move in two dimensions,such as in the X-direction (e.g., left and right, as shown in FIG. 11B)and the Y-direction (e.g., in and out of FIG. 11B, from the perspectiveof the reader). The displacement D2 may correspond to the pitch of theindividual emitter arrays included in the projector device 1102. Forexample, when the distance between the centers of neighboring emittersin an emitter array is two microns, the displacement D2 caused byactivation of the actuation component 1106A may be two microns, aninteger multiple thereof, a fraction thereof, or an integer plus somefraction thereof. In some embodiments, the displacement D2 may be afraction of the distance between the centers of neighboring emitters.For example, the displacement D2 may be one-half or one-third of thedistance between the centers of neighboring emitters, thus possiblyfacilitating higher operating frequencies for the actuation provided byactuation components 1106A and/or 1106B.

FIG. 11C depicts actuation of the actuation component 1106B, accordingto some embodiments. The activation of the actuation component 1106B maycause a displacement D3 of the waveguide configuration 1104 in thedirection of the arrow included in FIG. 11C. The displacement may besimilar to the displacement D2, such that the displacement D3 may be aninteger multiple based on a pitch of the emitter arrays included in theprojector device 1102 or may be a fraction thereof. In some embodiments,the actuation components 1106A and/or 1106B may alter the positionand/or orientation of the projector device 1102 and/or the waveguideconfiguration 1104, respectively, in order to steer one or more pupilreplications projected toward an eyebox 230 by a decoupling element orelements included in the waveguide configuration 1104.

In some embodiments, an actuation component 1106 may be disposed inbetween the projector device 1102 and the waveguide configuration 1104,as shown in FIG. 11D. The actuation component 1106D may be coupled to amirror 1108, or another suitable optical component, and may be activatedto cause the angle of the mirror to change as shown by displacement D4.As the mirror 1108 is driven between different positions, the light maybe coupled into the waveguide configuration 1104 may project out fromdifferent perspectives to provide the benefits of FIGS. 11A-D, asdescribed herein.

In some embodiments, the actuation component 1106A coupling theprojector device 1102 to the frame 105 may cause an angular orrotational movement of the projector device 1102 relative to thewaveguide configuration 1104 to cause movement of the pixels somedistance (e.g., a single pixel, a fraction of a pixel, an integermultiple of pixels, a number of pixels plus some fraction of a pixel,and so forth), as described above. In yet other examples, relativetranslation and/or orientation of the one or more monochromatic emitterarrays 402 relative to one or more optical components (e.g., one or morelenses) of their associated optical systems 406 may be employed to causesuch pixel movement. In other embodiments, controllably altering anindex of refraction of one or more of the optical components may providesuch pixel movement as well.

Activation of the actuation components 1106A and/or 1106B may providefor the projection of higher resolution images or for compensating forfaulty emitters included in one or more of the emitter arrays of theprojector device 1102. Examples of such operations are included in FIGS.12A-C, 13A-C, and 14A-B, which are described in greater detail below.

FIGS. 12A, 12B, and 12C depicts portions of images generated byembodiments of the display systems of FIGS. 11A-D showing a process ofresolution enhancement, according to some embodiments. FIGS. 12A-C showa consistent portion of a pupil replication 1200, according to someembodiments. The portion is highly magnified such that individual imagepixels are clearly shown as circular representations. As shown in FIG.11A, the display system 1100 may be in a first configuration. Forexample, the projector device 1102 may be in a first position. While inthe first position, an individual emitter array may produce rows ofimage pixels, including exemplary rows 1202A, 1202B, 1202C, 1202D, and1202E. These rows 1202 may be produced at a first time when theprojector device 1102 is in the first position. At a second time, afteractivation of the actuation component 1106A, the projector device 1102may be moved by a displacement D2 to a second position. The displacementD2 may be equal to one half the separation distance between adjacentemitters in the emitter array. While in the second position, anindividual emitter array of the projector device 1102 may be activatedto project image pixels in the exemplary rows 1204A, 1204B, 1204C,1204D, and 1204E. Accordingly, the image pixels shown in rows 1202 inFIG. 12A may be produced by the same emitters used to produce the imagepixels shown in rows 1204 in FIG. 12B.

The image pixels in the rows 1202 may be image pixels of a first imageor image portion, while the image pixels in the rows 1204 may be imagepixels of a second image or image portion. Because the light incident onthe eye 220 may persist for a brief amount of time, rapid oscillationbetween the first and second positions and projection of the twodifferent sets of image pixels may be perceived by the user as acontinuous image having more image pixels, thus providing some level ofresolution greater than that provided by a single, static image providedby projector device 1102 and waveguide configuration 1104. In someembodiments, the emitter arrays may be fabricated to include half thenumber of emitters for the desired image resolution. The extra spacebetween individual emitters may improve yield during fabrication. Forexample, an emitter array may be intentionally produced such that thenumber of pixels per unit of length is two, three, or four times greaterin a first direction than in a second direction. The extra space may beused for circuitry and to relax the fabrication constraints for somefeatures of the emitter array. In other examples, the extra spacebetween pixels may be less than the pitch between pixels (e.g., toincrease fabrication yield) while providing an increase in resolutiondue to the movement of the projector device 1102, as discussed above.

FIGS. 13A, 13B, and 13C show portions of images generated by embodimentsof the display system or display system 1100 of FIGS. 11A-D, showinganother process of resolution enhancement, according to someembodiments. FIG. 13A shows a pupil replication portion 1300 with afirst set of image pixels 1302. After an activation of the actuationcomponents 1106A and/or 1106B, the individual emitters of the emitterarray may be activated again to produce a second set of image pixels1304 as shown in FIG. 13B. Because the image pixels 1302 and the imagepixels 1304 may be shown in rapid sequence in time, the pupilreplication portion 1300 may appear to a user to simultaneously includeimage pixels 1302 and image pixels 1304. In this way, the display system1100 may produce a higher resolution image, e.g., an image having agreater number of image pixels than an individual emitter array hasemitters.

FIGS. 14A and 14B are portions of images generated by embodiments of thedisplay system 1100 of FIGS. 11A-D showing a process of imageenhancement, according to some embodiments. A pupil replication portion1400 shows a plurality of image pixels including one or more faultypixels. The pupil replication portion 1400 may include four exemplaryfaulty pixels 1402A, 1402B, 1402C, and 1402D. The faulty pixels mayresult from fabrication defects. For example, because of the size of theindividual emitters, one or more emitters in a given emitter array maybe nonfunctioning or inadequately functioning, such that the one or moreemitters cannot be relied upon to produce image pixels. Such faultyemitters may be identified at a calibration or testing stage duringfabrication of display systems, like the display system 1100.Neighboring emitters positioned along an axis of movement, e.g., oneither side of the faulty emitter, may be identified and operated asdescribed herein to compensate for the faulty emitter.

As shown in FIG. 14A, compensating pixels 1404A, 1404B, 1404C and 1404Dmay be produced by causing adjacent emitters to be operated at a higherbrightness than normal. The brightness of the compensating pixels 1404may be visually averaged by the eye 220 with the darkness of theneighboring faulty pixels 1402. When the projector device 1102 and/orthe waveguide configuration 1104 are moved from a first position to asecond position, a different neighboring emitter may be actuated at theincrease brightness level as shown in FIG. 14B. For example, FIG. 14Bshows that the compensating pixels 1406A, 1406B, 1406C, and 1406D may beproduced by neighboring emitters on the opposite side of the faultyemitters. In some embodiments, the compensating pixels may not beoperated at a different brightness level but may simply be operated atan average level of the intended pixel brightness and the neighboringpixel brightness. In some embodiments, three or more positions may beassumed by the projector device 1102 and/or the waveguide configuration1104 so that three or more pixels may be employed to illuminate a singlepixel position, as perceived by the user.

FIG. 15 is a flowchart of a method 1500 for enhancing images generatedby display systems or NEDs like those of FIGS. 11A-D, according to someembodiments. While the method 1500 may be depicted as an enumeratedsequence of steps or operations, embodiments of the method 1500 mayinclude additional or alternative steps before, after, in between, or aspart of the enumerated steps shown in FIG. 15.

Accordingly, some embodiments of the method 1500 may begin at a step1502, in which a processing device may direct emission of lightincluding a portion of a monochromatic image from a first monochromaticemitter array having a plurality of emitters of a first color disposedin a two-dimensional configuration. The monochromatic image may includea plurality of image pixels with at least one image pixel missing from acomplete instance of the monochromatic image. For example, thecontroller 330 of FIG. 3 may direct emission of light from amonochromatic emitter array 402A of FIG. 4C. The emitter array 402A mayinclude individual emitters like the microLEDs 600A and/or 600B of FIGS.6A and 6B, respectively. The monochromatic image may be produced by adecomposition of a full-color image into constituent monochromaticimages. The first projected image may include one or more missing orabsent image pixels for a variety of reasons. For example, themonochromatic emitter array 402A may include one or more faulty emittersthat are not capable of producing a desired brightness level, as shownin FIGS. 14A and 14B. In other embodiments, the missing image pixel maybe due to a configuration of emitters having spaces between rows suchthat gaps are present between rows of image pixels, as shown in FIGS.12A-C and as described herein.

At a step 1504, the light comprising the portion of the monochromaticimage may be coupled into a waveguide that produces a plurality ofinitial pupil replications from the portion of the monochromatic image.For example, the light produced by one of the emitter arrays of theprojector device 750 may be coupled into the waveguide 702A by acoupling element 712 in the coupling area 704A. The interaction of thereceived light with the decoupling elements 706A and 706B may produceone or more pupil replications, like the pupil replication 722, whichmay include a replication of each of the images 720A-C.

At a step 1506, a processing device may cause relative motion (e.g.,translation or/or angular orientation) between the first monochromaticemitter array and the waveguide from a first configuration to a secondconfiguration. For example, the controller 330 may cause the projectordevice 1102 of FIG. 11A to be displaced by displacement D2 as shown inFIG. 11B. Alternatively or additionally, the controller 330 may causedisplacement of the waveguide configuration 1104 as shown in FIG. 11C.This may be done by sending activation signals to the actuationcomponents 1106A and/or 1106B. The relative motion may cause a change inconfiguration of the projector device 1102 and the waveguideconfiguration 1104. In other words, one or both the projector device1102 and the waveguide configuration 1104 may be moved from a firstposition to a second position. Some embodiments may include additionalpositions. In yet other examples, such as those described above, such ascontrollably altering, or moving, one or more optical components of theprojector device 1102, may be employed produce the desired imageshifting.

At a step 1508, a processing device may direct another emission of lightcomprising an additional portion of the monochromatic image from thefirst monochromatic emitter array. The additional portion of themonochromatic image may add in the at least one image pixel missing fromthe complete instance of the monochromatic image. For example, theadditional portion of the monochromatic image may be similar to theimage pixels 1204A-E of FIG. 12B, which complement the image pixels1202A-E of FIG. 12A to form the increased resolution image included inthe pupil replication portion 1200 as shown in FIG. 12C. The additionalportion may be the image pixels 1304 of FIG. 13C, in some embodiments.Additionally, the additional portion may be provided by the compensatingimage pixels 1404 of FIG. 14A or the compensating image pixels 1406 ofFIG. 14B.

At a step 1510, the light comprising the portion of the monochromaticimage and the additional portion of the monochromatic image may beprojected as a plurality of enhanced pupil replications from thewaveguide toward an eyebox. For example, the enhanced resolution imagesrepresented by the image pixels shown in FIGS. 12C, 13C, 14A, and 14Bmay be projected from the waveguide 702A as one or more pupilreplications 722.

In some embodiments of the method 1500, directing emission of light thatmay include the portion of the monochromatic image may include directingemission of light comprising a first fraction of a total number of imagepixels of the complete instance of the monochromatic image. For example,the image pixels 1202A-E may be one-half of the image pixels included inthe desired image. In other embodiments, the first fraction may beone-third or one-fourth of the total image pixels.

Embodiments of the method 1500 may further include a step of directingthe other emission of light including the additional portion of themonochromatic image by directing emission of light comprising a secondfraction of the total number of image pixels of the complete instance ofthe monochromatic image. The second fraction may be one-half,two-thirds, three-fourths, or a smaller fraction, such as one-third orone-fourth. A sum of the first fraction of the total number of imagepixels and the second fraction of the total number of image pixels maybe approximately equal to the total number of image pixels of thecomplete instance of the monochromatic image. In some embodiments, morethan two portions of an image may be combined by portions emitted by themonochromatic image array at more than two positions. Accordingly, thetotal number of image pixels of the complete instance of themonochromatic image may be greater than a count of emitters in theplurality of emitters of the first monochromatic emitter array.

In some embodiments, the method 1500 may further include steps in whicha processing device, like the controller 330, may detect that a firstemitter of the plurality of emitters of the first color is a faultyemitter that is unable to produce a first image pixel of themonochromatic image. In these embodiments, the processing device mayfurther detect a location of the faulty emitter in the two-dimensionalconfiguration of the plurality of emitters of the first monochromaticemitter array and identify a compensating emitter from a plurality ofneighboring emitters that are adjacent to the first emitter and disposedalong an axis of potential movement. In some embodiments, the step ofdirecting the other emission of light including the additional portionof the monochromatic image may include directing the compensatingemitter to produce the first image pixel to add the at least one imagepixel missing from the complete instance of the monochromatic image. Theprocessing device may direct operation of the compensating emitter at anincreased brightness and/or operating duty cycle to compensate for thefaulty emitter.

In some embodiments, causing relative motion between the firstmonochromatic emitter array and the waveguide from the firstconfiguration to the second configuration may include activating anactuator system to displace the first monochromatic emitter array from afirst position to a second position and/or activating the actuatorsystem to displace the waveguide from a third position to a fourthposition. Activating the actuator system to displace the firstmonochromatic emitter array from a first position to a second positionmay include displacing a second monochromatic emitter array having aplurality of emitters of a second color disposed in the two-dimensionalconfiguration. The first monochromatic emitter array and the secondmonochromatic emitter array may be secured to a common platform, likethe PCB 408 of FIG. 4A or a more secure platform, to which the PCB 408may be secured. The first color and the second color may be differentcolors, such as red and blue or blue and green, etc.

Additionally, some embodiments of the method 1500 may include atangible, non-transitory computer-readable medium having instructionscorresponding to one or more of the described steps or operations of themethod 1500 stored thereon. When a processing device executes theinstructions, the processing device may perform one or more of the stepsof the method 1500.

As detailed above, the computing devices and systems described and/orillustrated herein broadly represent any type or form of computingdevice or system capable of executing computer-readable instructions. Intheir most basic configuration, these computing device(s) may eachinclude at least one memory device and at least one physical processingdevice.

In some examples, the term “memory device” generally refers to any typeor form of volatile or non-volatile storage device or medium capable ofstoring data and/or computer-readable instructions. In one example, amemory device may store, load, and/or maintain one or more modulescontaining instructions for executing the processes or steps describedherein. Examples of memory devices include, without limitation, RandomAccess Memory (RAM), Read Only Memory (ROM), flash memory, Hard DiskDrives (HDDs), Solid-State Drives (SSDs), optical disk drives, caches,variations or combinations of one or more of the same, or any othersuitable storage memory.

In some examples, the term “physical processor,” “processing device,” or“controller” generally refers to any type or form ofhardware-implemented processing unit capable of interpreting and/orexecuting computer-readable instructions. In one example, a physicalprocessor may access and/or modify one or more modules stored in theabove-described memory device. Examples of physical processors include,without limitation, microprocessors, microcontrollers, image processors,Central Processing Units (CPUs), Field-Programmable Gate Arrays (FPGAs)that implement softcore processors, Application-Specific IntegratedCircuits (ASICs), portions of one or more of the same, variations orcombinations of one or more of the same, or any other suitable physicalprocessor.

Although illustrated as separate elements, the modules described and/orillustrated herein may represent portions of a single module orapplication. In addition, in certain embodiments one or more of thesemodules may represent one or more software applications or programsthat, when executed by a computing device, may cause the computingdevice to perform one or more tasks. For example, one or more of themodules described and/or illustrated herein may represent modules storedand configured to run on one or more of the computing devices or systemsdescribed and/or illustrated herein. One or more of these modules mayalso represent all or portions of one or more special-purpose computersconfigured to perform one or more tasks.

In addition, one or more of the modules described herein may transformdata, physical devices, and/or representations of physical devices fromone form to another. For example, one or more of the modules recitedherein may receive image data to be transformed, transform the imagedata by, for example, splitting the image data into monochromaticimages, splitting monochromatic images into monochromatic imageportions, outputting a result of the transformation and using the resultof the transformation to project monochromatic images and image portionsthat may be combined by a waveguide configuration to general one or morepupil replications that are projected toward an eyebox. Additionally oralternatively, one or more of the modules recited herein may transform aprocessor, volatile memory, non-volatile memory, and/or any otherportion of a physical computing device from one form to another byexecuting on the computing device, storing data on the computing device,and/or otherwise interacting with the computing device.

In some embodiments, the term “computer-readable medium” generallyrefers to any form of device, carrier, or medium capable of storing orcarrying computer-readable instructions. Examples of computer-readablemedia include, without limitation, transmission-type media, such ascarrier waves, and non-transitory-type media, such as magnetic-storagemedia (e.g., hard disk drives, tape drives, and floppy disks),optical-storage media (e.g., Compact Disks (CDs), Digital Video Disks(DVDs), and BLU-RAY disks), electronic-storage media (e.g., solid-statedrives and flash media), and other distribution systems.

Embodiments of the instant disclosure may include or be implemented inconjunction with an artificial reality system. Artificial reality is aform of reality that has been adjusted in some manner beforepresentation to a user, which may include, e.g., a virtual reality (VR),an augmented reality (AR), a mixed reality (MR), a hybrid reality, orsome combination and/or derivatives thereof. Artificial reality contentmay include completely generated content or generated content combinedwith captured (e.g., real-world) content. The artificial reality contentmay include video, audio, haptic feedback, or some combination thereof,any of which may be presented in a single channel or in multiplechannels (such as stereo video that produces a three-dimensional effectto the viewer). Additionally, in some embodiments, artificial realitymay also be associated with applications, products, accessories,services, or some combination thereof, that are used to, e.g., createcontent in an artificial reality and/or are otherwise used in (e.g.,perform activities in) an artificial reality. The artificial realitysystem that provides the artificial reality content may be implementedon various platforms, including a head-mounted display (HMD) connectedto a host computer system, a standalone HMD, a mobile device orcomputing system, or any other hardware platform capable of providingartificial reality content to one or more viewers.

The process parameters and sequence of the steps described and/orillustrated herein are given by way of example only and can be varied asdesired. For example, while the steps illustrated and/or describedherein may be shown or discussed in a particular order, these steps donot necessarily need to be performed in the order illustrated ordiscussed. The various exemplary methods described and/or illustratedherein may also omit one or more of the steps described or illustratedherein or include additional steps in addition to those disclosed.

The preceding description has been provided to enable others skilled inthe art to best utilize various aspects of the exemplary embodimentsdisclosed herein. This exemplary description is not intended to beexhaustive or to be limited to any precise form disclosed. Manymodifications and variations are possible without departing from thespirit and scope of the instant disclosure. The embodiments disclosedherein should be considered in all respects illustrative and notrestrictive. Reference should be made to the appended claims and theirequivalents in determining the scope of the instant disclosure.

Unless otherwise noted, the terms “connected to” and “coupled to” (andtheir derivatives), as used in the specification and claims, are to beconstrued as permitting both direct and indirect (i.e., via otherelements or components) connection. In addition, the terms “a” or “an,”as used in the specification and claims, are to be construed as meaning“at least one of.” Finally, for ease of use, the terms “including” and“having” (and their derivatives), as used in the specification andclaims, are interchangeable with and have the same meaning as the word“comprising.”

What is claimed is:
 1. An apparatus comprising: a waveguideconfiguration including: a coupling area having at least one couplingelement configured to receive a plurality of monochromatic images,wherein each of the monochromatic images is of a predeterminedwavelength of light; a propagation area in which light, received via theat least one coupling element, moves within a length of the waveguideconfiguration; and a decoupling area that extends along the propagationarea and comprises decoupling elements that project a polychromaticimage toward an eyebox, the polychromatic image comprising themonochromatic images of the predetermined wavelengths of light.
 2. Theapparatus of claim 1, wherein the waveguide configuration comprises: afirst waveguide comprising: a first top surface; and a first bottomsurface disposed opposite the first top surface; and a second waveguidecomprising: a second top surface; and a second bottom surface disposedopposite the second top surface; and wherein: the propagation areacomprises a first propagation area portion between the first top surfaceand first bottom surface and a second propagation area portion betweenthe second top surface and the second bottom surface.
 3. The apparatusof claim 2, wherein the at least one coupling element comprises: a firstcoupling element on the first waveguide; and a second coupling elementon the second waveguide; and wherein: the first coupling element isconfigured to receive a monochromatic image of a first predeterminedwavelength of light; and the second coupling element is configured toreceive a monochromatic image of a second predetermined wavelength oflight, wherein the first predetermined wavelength of light and thesecond predetermined wavelength of light are different.
 4. The apparatusof claim 3, further comprising: a first monochromatic emitter arrayhaving a plurality of emitters of the first predetermined wavelength oflight disposed in a two-dimensional configuration; and a secondmonochromatic emitter array having a plurality of emitters of the secondpredetermined wavelength of light disposed in a two-dimensionalconfiguration, and wherein: the first monochromatic emitter array isaligned with the first coupling element; and the second monochromaticemitter array is aligned with the second coupling element.
 5. Theapparatus of claim 2, wherein the at least one coupling elementcomprises: a first coupling element and a second coupling element on thefirst waveguide; a third coupling element and a fourth coupling elementon the second waveguide; and wherein: the first coupling element isconfigured to receive a first monochromatic image of a firstpredetermined wavelength of light; the second coupling element isconfigured to receive a second monochromatic image of a secondpredetermined wavelength of light different from the first predeterminedwavelength of light; the third coupling element is configured to receivea third monochromatic image of the first predetermined wavelength oflight; and the fourth coupling element is configured to receive a fourthmonochromatic image of the second predetermined wavelength of light. 6.The apparatus of claim 5, wherein the waveguide configuration furthercomprises: an optical component disposed between the first waveguide andthe second waveguide to introduce an apparent distance between a firstimage plane associated with the first waveguide and a second image planeassociated with the second waveguide.
 7. The apparatus of claim 1,further comprising an additional coupling area having an additionalplurality of coupling elements, wherein the coupling area and theadditional coupling area are disposed on opposite sides of the waveguideconfiguration.
 8. The apparatus of claim 1, wherein the at least onecoupling element comprises at least one reflective optical element todirect at least one of the monochromatic images of the predeterminedwavelengths of light into the propagation area.
 9. The apparatus ofclaim 1, wherein the at least one coupling element comprises at leastone refractive optical element to direct at least one of themonochromatic images of the predetermined wavelengths of light into thepropagation area.
 10. The apparatus of claim 1, wherein the at least onecoupling element comprises at least one set of gratings to direct atleast one of the monochromatic images of the predetermined wavelengthsof light into the propagation area.
 11. The apparatus of claim 1,wherein: the propagation area replicates the monochromatic images toproduce a plurality of pupil replications of the monochromatic images;and the decoupling area projects the plurality of pupil replications ofthe polychromatic image toward the eyebox.
 12. A system comprising: afirst waveguide configuration comprising: a first waveguide having afirst top surface and a first bottom surface disposed opposite the firsttop surface; a first coupling element accessible via the first topsurface of the first waveguide, the first coupling element configured toreceive a first monochromatic image and propagate the firstmonochromatic image laterally within the first waveguide; a firstdecoupling element that projects a plurality of instances of the firstmonochromatic image toward an eyebox; a second waveguide having a secondtop surface and a second bottom surface disposed opposite the second topsurface, wherein the first decoupling element projects the plurality ofinstances of the first monochromatic image through the second waveguide;a second coupling element accessible via the second top surface of thesecond waveguide, the second coupling element configured to receive asecond monochromatic image and propagate the second monochromatic imagelaterally within the second waveguide; and a second decoupling elementthat projects a plurality of instances of the second monochromatic imagetoward the eyebox, the pluralities of instances of the first and secondmonochromatic images being combined to produce a plurality ofpolychromatic images.
 13. The system of claim 12, further comprising: asecond waveguide configuration including: a third waveguide having athird top surface and a third bottom surface disposed opposite the thirdtop surface; a third coupling element accessible via the third topsurface of the third waveguide, the third coupling element configured toreceive a third monochromatic image and propagate the thirdmonochromatic image laterally within the third waveguide; a thirddecoupling element that projects a plurality of instances of the thirdmonochromatic image toward the eyebox; a fourth waveguide having afourth top surface and a fourth bottom surface disposed opposite thefourth top surface, wherein the third decoupling element projects theplurality of instances of the third monochromatic image through thefourth waveguide; a fourth coupling element accessible via the fourthtop surface of the fourth waveguide, the fourth coupling elementconfigured to receive a fourth monochromatic image and propagate thefourth monochromatic image laterally within the fourth waveguide; and afourth decoupling element that projects a plurality of instances of thefourth monochromatic image toward the eyebox, the pluralities ofinstances of the third and fourth monochromatic images being combined toproduce another plurality of polychromatic images, and wherein the firstand second waveguide configurations are separated by a lens.
 14. Thesystem of claim 12, wherein the second waveguide comprises a cutout thataccommodates a housing of a first monochromatic emitter array thatproduces the first monochromatic image.
 15. A device comprising: ahead-mounted display comprising: a plurality of monochromatic emitterarrays, at least two of the plurality of monochromatic emitter arraysproducing monochromatic images of different wavelengths of light; and awaveguide configuration including: a top surface, a bottom surfacedisposed opposite the top surface, a coupling area having at least onecoupling element configured to receive the monochromatic images, apropagation area in which light received via the at least one couplingelement moves within a length of the waveguide configuration andreplicates the monochromatic images to produce monochromatic pupilreplications; and a decoupling area extending along the propagationarea, the decoupling area comprising decoupling elements that project aplurality of instances of a polychromatic image toward an eyebox throughthe bottom surface, the polychromatic image resulting from combinationof the monochromatic images of different wavelengths of light.
 16. Thedevice of claim 15, further comprising a controller in communicationwith the plurality of monochromatic emitter arrays to produce themonochromatic images as components of the polychromatic image.
 17. Thedevice of claim 15, wherein the top surface and bottom surface permitambient light to pass toward the eyebox such that the polychromaticimage is presented to the eyebox and an ambient environment is presentedto the eyebox through the waveguide configuration.